1. Technical Field
The present invention relates generally to probing apparatus using test probes, and more specifically to a test probe assembly that is easily disconnectable from the probe apparatus. More specifically still, the present invention relates to a quick disconnect probe assembly that readily breaks away from the probing apparatus upon collision with any other element.
2. Description of the Related Art
Probing apparatus for testing electronic components such as, for example, semiconductor wafers or circuit boards, are well known in the art. The probing apparatus use probe tips for providing electrical connection with device under test (DUT). These probe tips are small and do not endure the rigors of testing well; therefore, the probe tips are replaced frequently. The probe tips are small and they are placed on probe actuators or probe assemblies located well inside the probing apparatus. Thus, it is desirable to remove the probe assemblies from the probing apparatus to change the probe tips.
The probing apparatus usually has a coarse positioning system that moves with very high accelerations. If there is an error in the test file, a collision may occur that might damage either the components within the apparatus or the DUT.
Additionally, some DUT's are very thin and very small in relation to the overall positioned workspace in the probing apparatus. Typically, they are in a pocket in a support cradle that needs a minimum thickness for sufficient stiffness. This requires the probes to be in the pocket during testing, which leads to the possibility for collisions with the product support cradle from the side and rear, as well as with the opposing probe assembly from the front. Traditionally, slide bearing packages for collision compliance require a stack XY arrangement to give a 360.degree. freedom of movement. This stacking makes the mechanism fairly tall.
Trying to limit stack height is important in probe stacking design. First, the distance from the probe tip to the course positions and encoders impacts the accuracy of positioning the probe tip. Any aberration errors in the bearings and distortions in the structure due to settling vibrations are amplified by the distance from the encoder. The encoder head location is used to determine the probe tip location, thus, it is desirable to minimize the distance between the encoder head and the probe tip. Second, the taller the structure to which the probe tip is mounted, the more the probe assembly weighs and the less stiff it is. Moving of a large probe assembly mass should be minimized for coarse positioning performance to be optimal. Further, the structure to which the probe tip is mounted should be as stiff as possible so as not to vibrate significantly due to the acceleration experienced by the probe tip assembly during positioning.
Accordingly, what is needed is a probe tip assembly that is readily removable from the probing apparatus. Further, what is needed is a readily removable probe tip assembly that has collision compliance thus preventing damage to the expensive components or DUT within the probing apparatus. Furthermore, the probe tip assembly must have a low profile so as not to extend the probe tip too far above the course positioned thus leading to a decrease in accuracy of the tip positioning.